In the manufacturing process of a semiconductor device, various processing apparatuses (semiconductor manufacturing apparatuses) are used for subjecting an object to be processed, such as a semiconductor wafer, to an oxidation process, a diffusion process, a CVD (Chemical Vapor Deposition) process, and so on. One of the known processing apparatuses is a heat processing apparatus, such as a vertical heat processing apparatus of a batch type, which is capable of simultaneously heating and processing a number of objects to be processed.
Generally, in the vertical heat processing apparatus, a number of wafers, which are held by a boat as a holder in a tier-like manner with predetermined intervals therebetween, are received in a processing vessel. The wafers are heated by a tubular heater that is disposed to surround the processing vessel, so that the wafers are subjected to a predetermined heating process. The heater is generally formed by arranging a linear heating resistor on an inner circumference of a tubular heat insulating member.
It has been proposed to construct such a vertical heat processing apparatus in such a manner that, in order to improve speed and/or throughput of a process by promptly lowering temperature of wafers after the heating process, an atmosphere in a space between the heater and the processing vessel can be discharged, and that a cooling fluid can be introduced into the space to forcibly cool the processing vessel (see, for example, JP7-99164A and JP11-260744A).
Recently, in accordance with the increased number of wafers to be processed, there is a tendency to elongate lengths of the heater and other members incorporated in the heat processing apparatus (e.g., the processing vessel and the boat). Thus, temperatures of the incorporated members are prone to be non-uniformly lowered during the above forcible cooling step. This may result in non-uniformity in product quality of wafers.
On the other hand, when a diameter of a cooling-fluid nozzle is enlarged to increase a flowrate of the cooling fluid, heat dissipation caused by leakage of radiant light from the cooling-fluid nozzle is increased. This may invite problems in that uniformity of temperature inside the heater is degraded, and that temperature outside the heater is elevated.
In the art disclosed in JP11-260744A, a quick-cooling port opened obliquely upward is formed in a molded heat-insulating member, and a cooling medium introduced through the quick-cooling port forms a rotating flow. Thus, non-uniformity of temperatures of the incorporated members during the forcible cooling step can be restrained to a some degree. However, in order to supply the cooing medium to the quick-cooing port, it is necessary to dispose the predetermined number of vertically extending cooing-medium introducing paths in the molded heat-insulating member, which complicates the structure.